like the title says is it really necesary to use a flexible backing with a rotary using a *foam* pad??

 

it's not necessary but it will help avoid hot spots and burned paint. Plus it will let you cover the curves more effectively.

 

well i ordered it, was only $20 so better be safe... thanx badtz

 

I've used both...VERY worth it to get a flexible backing plate.

 

Unless you're doing refinishing of the paint like orange peel removal I'd use a flexible backing plate that is smaller than the PAD. It will save you a lot of grief if you run the pad / plate into some areas of the body contour that the rigid PAD would otherwise hurt.
Besides being safer, I also think it's a lot easier to work with.

Either way - not too much pressure on the PAD, let the machine spin the PAD rather freely.